I have just purchased a used Gerber Sabre 404. During orientation, the X, Y and Z axes move to their stops and then slowly move away about 1/4 - 1 inch (judging by eye). However, it errors out with one of two errors on the teach pendant, depending on whatever mood it's in.

The first error is
"!!!!!!ERROR!!!!!!
Y AXIS"

Per the troubleshooting guide, this is caused by a (front) limit switch problem. I have traced the front limit switch back to the main circuit board inside the electronics cabinet and determined that it is working properly. I have my continuity tester attached to the two lines (again -- performing testing at the board) using the audible beep on my multimeter. When I turn the lead screw back and forth by hand (power disconnected), I can hear the beep on my multimeter going on and off, as the probe on the carriage enters the magnetic limit switch. It is stable, repeatable and it has not yet missed picking up the signal after moving it back and forth a dozen times by hand. I'm pretty confident that it's getting the signal to the board. So is the board bad? Or is there some type of problem in here? Is there a full reset that can be done?

Sometimes, however, it will have an error that says
"!!!!!!ERROR!!!!!!
SYSTEM: Orienting!"

I cannot find anything in the users manual that addresses this.

Anyone know anything about these circuit boards? Is there an online source for these pieces other than Gerber? Or are these boards proprietary?

I saw the post by @ned_seven that shows replacing the driver with a Machdrives system, but I'm hoping that my repair won't have to be that drastic.